The former home of the French Monarchy, today a big tourist attraction. The two houses of the French Parliament occassionally meet here to see the President, or to discuss changes to the constitution.
It was a palace when there used to live kings [i.e: Marie Antoinette]. In that palace lived the king the queen and sometimes their families as well. Now is just a museum.
2 Floors for the main areas. There is a multi tiered opera and a chapel which you can count as you like. Additionally there are some lower cellar areas but I think that you should not count those.